Conical or cylinder grinding mill



A. c. B|TTNER.

CON!GAL 0R CYLINDER GRINDING MILL.

APPLICATION FILED APR. 18. 922.

1,480,432. Patented Sept. 26,1922.

2 SHEETSSHEET lt uc H 501 A C. BITTNER. CONICAL 0R CYLINDER GRINDINGMlLL Patented Sept. 26, 1922.

2 5HEETS-SHEET 2.

APPLICATION FILED APR.18, 1922.

Patented Sept. Z6, i922.

W TE e mania V'AT'DALUS c. BITTNER, or CLINTON,'IOWA.

CONICAL OR CYLINDER GRINDING MILL.

Application filed April 18, 1922. Serial No. 554,798.

To all whom it may concern:

Be it known that I, ATTALUs C. BITTNER, a citizen of the United States,residing at Clinton, in the county of Clinton and State of Iowa, haveinvented new and useful Improvements in Conical or Cylinder GrindingMills, of which the following is a specification.

separate the fine material and at the same time prevent the grindingcharge from be ing discharged out of the mill before thorough grindingensuesfiand also to obviate the outward passage or discharge of thegrinding media such as steel balls or pebbles or any grinding load beingused in the mill with the material under normal feed of the material tothe mill. The improved device is also provided with means to take careof the overload in the mill.

In conical or cylindrical mills in which material is disposed forgrinding purposes through the medium of steel balls or other deviceswhere the mills are lacking in any particular means to control thedischarge of the grinding material, the,coarse or unground material andthe steel balls or grindin media are always liable to pass-out throughthe discharge opening with the fine material, and necessitate the returnof the coarse material and grinding media into the mill through theintake end of the latter. Moreover, in this class of mills where thereis no controlling discharge means at the outlet, a considerable portionof the material that, has been ground sufficiently fine is neverdischarged, but is turned over and over and remains in the mill andprevents the effective working of the grinding load. The improveddischarge screen or grate having a lifting function overcomes thesedisadvantages and considerable econom results by reason of the fact thatthe load 1s constantly 'ing cylinder where it would kept where it cangrindlng operation. 18 obviated as well carrying the grinding load andcoarse material that may be discharged from the mill back to the intakeend of the tube. In addition the improved discharge controlling meansembodying the features of the present invention is effective inliberating all of the fine materials or fines through the outlet of thecylinder as soon as it reaches the said outlet, and thereby preventsalso the return of this finely ground material to the grindact as acushion and hlnder the grinding of the coarser mat'erial. The improveddischarge controlling means or screen or grate and lifter, therefore,automatically and effectually operates to' overcome the numerousdisadvantages in prior mills of the type for which proved device hasbeen devised.

The invention consists in the preferred construct-ion and arrangement ofthe several parts which will be more fully hereinafter described andclaimed.

In the drawings:

Fig. 1 is a longitudinal vertical section of a cylindrical mill showingthe improved discharge device applied thereto;

Fig. 2 is a detail perspective view of the improved discharge devicelooking towards the inner side thereof; I

Fig. '3 is a transverse vertical section through the improved dischargedevice;

-Fig. 4 is a section on the line 4r4:, Fig. 3; and

Fig. 5 is an end elevation of the improved discharge device lookingtowards the outer end of the same.

i The numeral 5 designates a cylinder havmg a reduced or conicallyshaped outlet extremity 6 and the opposite end 7 also conically reducedand having a feed chute 8 centrally communicating therewith. The rear orreceiving extremlty 7 is provided with, the usual driving gear 9 forrotating the; cylinder by suitable mechanism, and to facilitaterotation, the cylinder is supported on pedestals 10 on which are securedbearing blocks 11 and 12. Theopposite extremities or ends of thecylinder are also provided with trunnions 13 and 14 for a purpose whichwill be readily understood, these parts being common in the art relatingto this type of grinding mills. The trunnion 13 has a continuousslightly flared discharge spout 15 the im- I around the open end 16constituting the discharge outlet of the cylinder. Within the cylindergrinding devices such as balls, pebbles and other grinding media areplaced and serve by impact to pulverize or grind the material fed intothe cylinder through the intake, or inlet end or extremity 7 by thechute 8. v

The present invention relates particularly to discharge means, andthough shown applied to the rotatable cylinder or drum 5 of common form,it may equally well be used in connection with any other analogousgrinding container, the shape of the cylinder or container not in theleast controlling the function and operation of the improved dischargemeans or organization which is shown in detail by Figs. 2 to 5,inclusive. The improved discharge means or organization.

comprises a truncated conical casing 17 formed from a suitable thicknessof sheet metal and having an outside dimension approximately the same asthe interior dimension of the outlet or discharge end of the reducedconical extremity 6 of the cylinder 5. Extending centrally through othecasing or body 17 of the improved discharge means or organization is atube 18 fully open at both ends and having the double function ofservingas a hollow core for the discharge means and especially as anoverload outlet.

Radiating from the tube 18 are segmental screens or grates 19 continuingfully outwardly to the inner surface of the surrounding casing or shell17 and peripherally fixed to the "latter. These segmental screens orgrates also continue from the inner end to the outer end of the casingor shell 17, and from the radial edges 20 of the said screens or grates19 imperforate concavo-convex sheet metal sections 21 extend and arealso continued outwardly from and peripherally secured to the innersurface of the surrounding casing or shell 17. The sections 21 are ofsegmental form and each section has its outer reduced edge 22terminating coincidently with and secured to the outer edge of thescreen or grate next in advance of that from which the inner edge 23 ofeach screen or grate starts. This alternate arrangement ofthe screens orgrates 19 and the sheet metal concavo-convex sections 21 is regularlycarried out around the interior of the casing or shell 17 and the tube18. The convex sides of the imperforate sheet metal sections 21 aredisposed innermost, or at the enlarged receiving end of the improveddischarge means. By this arrangement of the sections 21 the outer convexsurface or sides thereof are adjacent to the outer sides of the screensor grates 19, so that when the ground material is discharged through thescreens or grates, it is taken up and forced outwardly through the outeror outlet end ofthe discharge means.

The improved discharge close against the inner enlarged receiving end ofthe improved discharge means or organization. This ring 24 will not inthe least interfere with the effective operation of the discharge means,as it will preferably be of about the same thickness as the metal of thecasing or shell 17.

The operation of the improved grinding or reducing mill hereinbeforedescribed is the same as in Well known devices of this character, andthe material to be ground or reduced is admitted into the cylinder 5through the chute 8 and the cylinder then rotated to cause the balls,pebbles or other grinding media to comrninute or pulverize the material.In well known grinding mills of this type the grinding material isdischarged through a hollow trunnion at the discharge end similar to thetrunnion 13 with the spout 15, and the disadvantages incident to thisunrestricted or free outlet has been hereinbefore specified and 7consists mainly in the discharge of coarse material and the grindingmedia with the fine material and the necessity of replacement of thecoarse material and grinding media through the intake end of thecylinder by Way of the chute 8. In the present improved construction thedischarge means or organization and comprising the screens or grates 19and the imperforate concavo-convex segmental sections 21 arranged ashereinbefore specified, the finely ground material or fines is taken upand delivered or discharged through the screens or grates 19 and thenpushed or propelled outwardly by the concave front or outer sides of thesections 21 through the outlet end of the improved discharge meansaround the center tube 18. At the same time under normal load of themill the coarse material that might otherwise escape together with thegrinding media that may shift or settle towards thedischarge end of thecylinder will 'be pushed backwardly by the inner convex sides of thesegmental sections 17, and a material amount of agitation or throwing upof the coarser material and grinding media will be effected adjacent tothe inner end of the discharge means,"and as a consequence, there willbeless tendency-of the finely ground material to settle towards the bottomor cover and shield the coarse or unground material, and therefore thegrinding media will be free to operate on the coarse material and reducethe same to the predetermined degree of fineness. However, it will beunderstood that the fine material will be taken up and rapidlydischarged through 'the screens or grates 19, and in those grindingmills where the cylinders are canted 38o chine and the adjacent convexinner side-of each imperforate section .21, a pocket will be formed atthe inner portion of the discharge means, and through the medium of thispocket formation, which continues around the discharge means, a regularliberation and outlet of the finely ground material or fines will ensue.

In practical operation of mills of this character the material to beground isu'sually fed automatically thereinto, the speed of theoperation or process of grinding varying with the toughness and hardnessof the material being ground, and consequently, the machine isoverloaded at times. If no provision is made to take care of thisoverload, the entire machine soon becomes choked, for the reason thatwhen the machine is overloaded the grinding process is retarded. To takecare of this overloading of the mill or machine, the tube 18 is used,the latter not only serving as a supporting means as hereinbeforedisclosed, but also as an overflow device. When the machine isoverloaded, not only the material to be ground but the grinding mediamay pass through this tube, to relieve the over-charge of the mill ormaand subsequently the material or grin ing media thus dischargedthrough the tube may be taken back and reinserted in the c linder orbody of the mill through the fee ing means therefor. Under normalconditions, however, none of the material to be ground or grinding mediawill be delivered through the improved discharge means, the finematerial, or the material that has been successfully ground, being theonly part of the contents of the cylinder that isdelivered through *theimproved discharge means.

It wi 1 also be seen that a straight screen wall and a conveximperforate bufling wall adjacent to the screen wall will continue insequence around the interior of the casing or shell 17, and as the imroved discharge means regularly rotates with the cylinder, it. will havea lifting action with respect to the fine material and a repellantaction with respect to the coarse material and grinding media, which isof material advantage in a discharge means for a mill of this type.Moreover, the disposition of the screen walls and imperforate convexbush ing walls around the interior of the casing or shell will have theeffect of drawing the fine material into the discharge device to thebest advantage for discharge purposes and .facilitate the outlet of thefinely ground material.

It will be understood that the proportions and dimensions of theimproved discharge device as. a whole may be varied at will inaccordance with the dimensions of the adapted to be applied and also inaccord ance with the character of the material to be round.

hat is claimed as new is: a 1. A grinding mill of the characterspecified,-having a discharge device comprising radial screen wallsarranged in alternation with concavo-convex closing sections.

2. In a grinding mill of the class specified, a rotating container forreceiving material to be ground and grinding media, and a dischargedevice secured to one end of the cylinder and rotating with the latter,the discharge device being provided with alternately arrangedoutletscreen. walls and closed walls.

3. In a grinding-mill of the class specified, a rotatable grindingcylinder, and a discharge device secured to one end of and rotating withsaid cylinder and provided with radially arranged outlet screen wallsand alternate concavo-convex closed walls extending from the inner endedge of one screen wall to the"outer end edge of. the next screen wall.

4. In a grinding mill of the class specified, a rotatable grindingcontainer, and

fied, a rotatable grinding container, a discharge device secured to androtatable with the container and having radial screen walls arranged inalternation with concave-convex closing sections, and a central outletmeans to take care of the overload of the mill.

In testimon whereof I. have hereunto set my hand 1n presence of twosubscribing witnesses.

. ATTALUS C. BITTNER. Witnessesz' FLoRnNoaG. SHIPE,

ELsm I. OULP.

